import java.util.Scanner;

public class Ketang4{
        public static void main(String[] args) {
            Scanner scanner = new Scanner(System.in);
            System.out.println("请输入2个数");
            int n=scanner.nextInt();
            int m=scanner.nextInt();
            int result=sum(n,m);
            System.out.println(result);

        }
        private static int sum(int n,int m) {
            int sum = 0;
            for (int i = n; i < m; i++) {
                if (i % 2 == 0) {
                    sum = sum + i;
                }
            }
        return sum;}
    }








